There are a number of metal machining processes where it is essential that the working tool and/or workpiece follow a defined by a translational or orbital path as the tool works a given workpiece surface. For example, jig boring or grinding machines are well known machine tools where a boring, grindirg or polishing wheel, rotating on its own axis, is further made to revolve in a planetary or orbital path in the finishing of circular holes or recesses within metal workpieces. By placing the workpiece on an orbital table, the combined orbital motions of the working tool and the workpiece makes possible the working of complex surfaces other than round.
More recently, orbital grinding machines have come into use which do not utilize rotating grinding wheels, but rather being a tool and workpiece together, at least one of which is ortiting without rotation against the other. In this application, the working tool is usually formed of a rather hard material and typically has a three dimensional configuration in it working face. By orbiting either the tool or the workpiece, or both, while the two are in contact and biased against each other, using a rather small radius of orbit, the negative configuration of the tool is worked into the workpiece. Because of the orbital motion of either the tool or workpiece, the resulting machined configuration in the workpiece cannot be of an identical size to that of the tool. However, rather complex, intricate and exacting three dimensional configurations can be produced by proper allowance for the orbital action between the tool and the workpiece.
Other recent and advanced machining processes, such as electrical discharge machining, either sequentially or in multifunctional singular operations are utilized which in some applications depend on orbital motion of the work tool and/or workpiece to machine shapes not attainable in any other practical way and at levels of finish and accuracy which are exceptional.
The machine tools and techniques mentioned above, usually utilize conventional X-Y tables which are expensive and tend to be rather large due to the complex motion creating hardware. The complex nature of the hardware leads to a rather high power loss and accuracy factors that are less than desired.